Sir Philip Green has threatened MP Frank Field with legal action after the politician claimed to have seen leaked details of the official investigation into the BHS pension crisis.

Last week Field told a radio programme that he has new information from the original probe launched by The Pensions Regulator into the £571m BHS pension black hole left by the owners when the high street chain collapsed in April last year.

But Green, who sold-off the chain for £1 to serial bankrupt Dominic Chappell a year before the retailer shut down, has said any disclosure of debt details would breach data protection and pensions laws.

In a letter to the chair of the work and pensions committee, Green said: “You claim to have dynamite evidence against me. How can this be the case when the document you referred to on the radio is not new; it is a document produced by the regulator last year?”

The billionaire boss of the Arcadia group added that once the regulator came to him with their findings he immediately paid £363m directly into the pension scheme – a sum he said was agreed with investigators.

Last year’s parliamentary investigation into the collapse led to accusations by Field and his fellow Labour MP Iain Wright that Green represented the “unacceptable face of capitalism” and was overseeing the “systematic plunder” of the company.

Green and other investors were paid £586m in dividends, rent and interest during his 15-year ownership of BHS.

The war of words between the pair has continued to rumble in recent months.

According to this latest letter, seen by the Guardian, Green now considers the pensions inquiry closed and the deficit resolved.

“This sum of money was paid on a strictly voluntary basis,” he wrote. “A settlement was reached with the regulators and I was given statutory clearance by them.”

He finished the letter with a warning to the MP for Birkenhead that he would be receiving a formal legal notice from his lawyers to help him “understand the content and seriousness of your actions”.

In April this year, Field warned Green that he could still be stripped of his knighthood amid concerns that the lump sum he paid back to the pension pot would not cover costs.

Speaking in April, Field said: “It’s rather good that [Theresa May] is waiting for all the reports to come in before she makes a recommendation to the honours forfeiture committee. The case against Sir Philip will continue in the new parliament.”

Last year MPs passed a motion calling for Sir Philip Green to be stripped of his knighthood but politicians have no real power over the honours system and so were only able to voice views on the matter rather than take away the title.